Create Mass Credit Memo for existing AR invoices

Summary:

We have thousands of outstanding legacy invoices that needs to be cancelled in OneERP. Since we have learned we cannot mass cancel completed/accounted AR invoices and there is no way to delete them in UI. We are planning to create credit memos against these invoices. Is this possible? If this is possible thru FBDI , Rest API or any other method. Can someone provide us the steps on how to do it?

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Version (include the version you are using, if applicable): Oracle Fusion

Code Snippet (add any code snippets that support your topic, if applicable):